Week 1 Spur Gear Challenge

Aim : To perform static structural analysis of Spur Gear to find out the location of possible fracture.

Objective :

1) Carry out a static structural analysis to find out Equivalent stress, Total deformation and Stress intensity.

2) Using three materials Cast Iron(ductile), Cast Steel and Cast Bronze for analysis.

3) Comparing the three results on the basis of solution.

4) Choice of material after the determining the solution result.

Introduction :

Static structural analysis : A static structural analysis determines the displacements, stresses, strains and forces in structures or components caused by loads that do not induce significant inertia and damping effects.

Methods of solutions to be performed in the given geometry are as follows :

1) Equivalent stress :

The von Mises stress is used to predict yielding of materials under complex loading from the results of uniaxial tensile tests. The von Mises stress satisfies the property where two stress states with equal distortion energy have an equal von Mises stress.

2) Total deformation :

Change in the shape of a body caused by the application of a force (stress). Deformation is proportional to the stress applied within the elastic limits of the material . Directional deformation can be put as the displacement of the system in a particular axis or user defined direction. Total deformation is the vector sum all directional displacements of the systems.

3)Stress intensity :

It is an important parameter to determine the fracture of cracked member or calculating the rate of crack growth at certain area in the geometry.

Procedure :

1) For both cases, we use static structural tool in the analysis system tool box to define the geometry and other input parameters for the same.

2) In the engineering data we input the material and its properties. If we dont have the desired material to use for analysis we can always input the material by ourselves to create a new material with the properties mentioned below:

For Cast Bronze property

For Cast Steel property

3) Input the given spur gear geometry from the geometry tab. Naming the left and right hand side gears.

4) In connection, we have to define the contact faces between the two gears of the geometry by selecting and deselecting as contact or target bodies. In contacts under connection tab we define the type of contact as frictional contact from right to left.

5) To define type of joint we use contact tab and specifying the body to ground connection type. Also scoping the geometry by selecting the inner face of the geometry.

6) By opening the modelling the tab, we mesh the geometry with element size of 0.8mm. Generating the mesh thereafter by right clicking on the Mesh icon.

7) After defining the contacts and joints, we open analysis setting where we define the revolution of gear in 6 steps from 0 to 180 degree at different time steps.

8) We select the first joint load from the static structural analysis tab as rotational type and defining the angles till 180 degree in 6 steps to its each corresponding step. The left gear would be rotating anti-clockwise motion.

9) Now we define the right hand side gear with load joint by inputting the value of 10 N.m for every step in moment. This right gear would be rotating in clockwise direction.

10) For solving the solution we insert the von mises equivalent stress, total deformation and stress intensity,

For Case 1, Cast iron(ductile)

Equivalent stress :

Total deformation :

Stress intensity :

Status :

Pressure :

For Case 2, Cast Steel :

Equivalent stress :

Total deformation :

Stress intensity :

Status :

Pressure :

For Case 3, Cast Bronze :

Equivalent stress :

Total deformation :

Stress intensity :

Status :

Pressure :

Results :

Sr.No	Solution type	Cast Iron	Cast Steel	Cast Bronze
1.	Equivalent stress Von-Mises (Maximum)	112.69 MPa	209.05 MPa	83.28 MPa
2.	Equivalent stress Von-Mises (Minimum)	9.1612e-10 MPa	1.5905 MPa	3.4505e-10 MPa
3.	Total deformation (Maximum)	30 mm	30 mm	30 mm
4.	Total deformation (Maximum)	18.5 mm	18.5 mm	18.5 mm
5.	Stress Intensity (Maximum)	121.01 MPa	225.86 MPa	91.224 MPa
6.	Stress Intensity (Minimum)	9.4387e-10 MPa	1.7304e-9 MPa	3.3889e-9 MPa

Conclusion :

1) The maximum equivalent stress can seen higher in Cast steel and lowest in Cast bronze.

2) Maximum total deformation is same throughout all the cases.

3) Maximum stress intensity is higher in Cast steel and lower in Cast Bronze.

4) Choice of material here should be Cast Iron, because Cast iron is harder than the Cast bronze. Also if we look into the physical properties in manufacturing point of view, while iron has a melting point of 1600 degrees Celsius, bronze has a melting point of 1000 degrees Celsius. Well, bronze is easier to cast, but it is harder to forge. When heated, iron retains heat, whereas bronze cools immediately. Cast iron is relatively easy to cast, as it pours easily and doesn't shrink as much as steel.